Friendships have been shown to protect youth against the development of emotional adjustment problems. Peer relationships may be especially important for youth who currently experience emotional difficulties like depression and anxiety. Ironically, the friendships of such youth may be adversely affected by their emotional problems, which could potentially exacerbate symptoms of depression and anxiety. While the link between youths'internalizing symptoms and peer group rejection has been established in previous studies, almost nothing is known about the processes by which youth with internalizing symptoms come to suffer problems in their dyadic friendships. The current study fills an important gap in the literature by examining mechanisms by which youth with internalizing symptoms come to experience rejection by a friend. Moreover, even less is known about the friends of youth with internalizing symptoms. That is, although a contagion effect has been found for depression in adolescent friendships, very little is understood about the mechanisms by which youths'depression may spread to their friends. The current study also extends the existing literature by examining processes by which friends of youth with internalizing symptoms come to experience emotional distress themselves. Survey and observational data for 200 adolescent friendship dyads (N = 400) will be obtained to examine specific conversational processes which may mediate the associations of youths'internalizing symptoms and friendships over time. With the exception of few established interventions (e.g., multi systemic therapy), psychotherapy rarely utilizes the peer context in the treatment of youth with internalizing problems. Because empirical research supports the idea that internalizing problems both contribute to and are an outcome of peer relations difficulties, the peer context cannot be overlooked. By identifying potential mechanisms by which youth may come to experience increased socio-emotional distress in the interpersonal context, the current research will inform the development of therapeutic interventions which may target specific problematic behavioral and interpersonal processes that may exacerbate or contribute to emotional and friendship problems.